1. Field of the Invention
This invention generally relates to wireless communication systems including a wireless communication device having cryptographic functions requiring random data inputs (e.g., to generate cryptographic keys, certificates and the like).
2. Related Art
Well known cryptographic processes (e.g., for generating cryptographic keys, certificates and the like) often require a random data input from time to time. There are many known forms of software and hardware random number generators that may be used and many of them depend upon input of a random “seed” data.
Initializing random seed data may be supplied during manufacture or may be provided subsequently by a desired known technique. However, for various reasons, it is possible that the randomness of data in the random seed may be less than desirable. For example, when a mobile wireless communication device is provisioned for the first time at the factory, it may leave the factory with a random seed that is not entirely random with respect to other devices manufactured and provisioned at approximately the same time. Furthermore, for various reasons it is sometimes necessary (or at least desirable) to “wipe” all stored data (including the stored random seed data) from the device memory. This may happen, for example, when updating software, recovering from abnormal conditions—or merely for enhanced security purposes subsequent to some period of uncontrolled access to the device. For example, it is conceivable that if an unauthorized entity gains access to the device, then information might be ascertainable that relates to the content of a stored random seed and thus possibly make future cryptographic communication sessions vulnerable to unauthorized decryption. In other words, the device may pass out of possession of the authorized user (either intentionally or unintentionally) and thus become an untrusted device—unless suitable randomness can be restored to the random seed data stored in the device.
Accordingly, there is a needed ability to securely add randomness to a wireless communication device within a wireless communication system.